Osseointegrated dental implants are typically metallic or ceramic screws that are placed in the jawbone for supporting artificial teeth after the loss of natural teeth. Replacement of the maxillary teeth is often a challenging surgical procedure when the remaining maxillary bone has insufficient height to support the implant. One surgical technique for augmenting the maxillary bone includes injecting a regenerative material, such as autogenic, allogeneic, xenogeneic, or synthetic bone graft, into the vicinity of the maxillary bone. The regenerative material forms additional bone mass that integrates with the existing maxillary bone, providing the necessary alveolar height to support the implant.
Bone augmentation procedures are often surgically difficult to perform, and are associated with complications, including infection of the maxillary sinus. The top of the maxillary alveolar ridge forms the floor of the maxillary sinus, and is covered by a thin membrane known as the Schneiderian or subantral membrane. In one surgical procedure, known as a closed or internal sinus lift or elevation procedure, the surgeon drills a bore through the maxillary alveolar ridge from the oral cavity at the desired location of the implant. The bore penetrates the ridge to below the Schneiderian membrane. The surgeon injects the regenerative material through the bore to below the membrane, forming a cavity defined by the top of the ridge and the bottom of the membrane, which cavity occupies a portion of the space initially occupied by the maxillary sinus.
To prevent potentially serious complications, the surgeon must be careful not to perforate the Schneiderian membrane. This is often difficult, because of the delicacy of the membrane, and the restricted access afforded by the closed approach.
Hydraulic sinus lifting is performed by applying hydraulic pressure between the sinus floor and the Schneiderian membrane. The hydraulic elevation can be performed via a crestal or lateral approach. Once the membrane is elevated, using a hydraulic, closed, or lateral window technique, a bone graft material is applied, typically using one of two conventional techniques. The first conventional technique is the mechanical insertion of bone graft, which is formulated in small particles. This technique is manually demanding, and it may cause application of unequal stresses to the membrane, which may result in perforation of the membrane. The second conventional technique is the injection of bone graft in a gel formulation by applying the same principles of hydraulic elevation used during raising of the membrane.